2) Dead load, trolley with no hook load in any position on the
bridge girders, and non-operating wind load applied perpendicular to the bridge
girders. The resultant of all forces and moments must be within 80 percent of the
distance from the crane's geometric center to the main gudgeon pin axis.
3) Dead load, trolley with rated hook load in any position on the
bridge girders, and collision force. The resultant of all forces and moments must
be within the main gudgeon pin axes.
Collision force is due to the full impact of the crane hitting the end
stops or the bumpers of another crane at its rated speed but with the power off.
The energy absorbing and decelerating characteristics of the bumpers are
considered in determining the collision force.
In the case of semi-gantry cranes, the crane configuration is assumed to
be that of a gantry crane (symmetrical to the gantry end of the crane).
Container Handling. Stability cases and stability requirements for
cranes with a head block are identical to those in paragraph 188.8.131.52.a, except
that the total weight of head block, spreader, and container is used in place of
"rated hook load" and only the weight of head block is used in place of "no hook
Supplementary Design Features. Additional structural design features
must be considered and included in the original design to enhance the safety,
permit efficient field assembly, and ease the maintainability of cranes.
Accessibility Provisions. The sizing and configuration of accessibility
structural items such as stairs, handrails, walkways, platforms, and ladders
are governed by OSHA 29 CFR 1910 requirements. The OSHA requirements apply to all
crane types. Some industry standards specify additional requirements, as in the
case of CMAA #70. For cranes which do not have similar comprehensive design
criteria for walkways and platforms, NCC specifies two load cases.
Dead load and distributed load of 50 pounds per square foot (35
pounds per square foot for boom walkways).
Dead load and a concentrated load of 350 pounds (250 pounds for boom
walkways) in any location.
The maximum stresses for both load cases are limited to 100 percent of
AISC values for the particular material. Other structural requirements of
paragraph 5.1 for welding and bolting, also apply.
Test Weights. Cranes designed for handling of items (such as containers)
have dedicated test weights for periodic load testing. In the case of container
cranes, the test weight must be designed for engagement by the spreader twist
locks to duplicate the operational loading of the spreader. Cranes operating in
weights to maintain order and neatness in the magazines. Dedicated test weights
should be considered for other specialized crane operations.